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Hetaerina americana Fabricius, 1798 has a long and irresolute taxonomic history. Several synonyms have been suggested (H. californica Hagen in Selys-Longchamps, 1859, H. basalis Hagen in Selys-Longchamps, 1859, H. texana Walsh, 1863, H. scelerata Walsh, 1863, etc.), related to the variation in the size of the wing spots as well as to the morphology of the male cerci. However, Calvert (1901) suggested that H. americana represents one variable species. Nevertheless, Vega-Sánchez et al. (2019) through a genetic and morphological analysis presented evidence to propose that H. americana represents a species complex. In the present work, we describe a new species that belongs to this complex: H. calverti sp. nov. The morphological characteristics by which males and females of H. calverti differ from H. americana are highlighted. The most important character for the differentiation of males is the shape of the cerci and the size of the individuals (when the two species are in sympatry). In females, the main differences are in the shape of the intersternites and the medio-dorsal carina of the last segment of the abdomen. Some generalities about the biology of the species are presented, including geographical distribution patterns and genetic divergence data. [urn:lsid:zoobank.org:act:F5C329AE-7A00-4979-8A0D-A13D869E54B1]

The damselflies Hetaerininae, a subfamily of Calopterygidae, comprise four genera distributed from North to South America: Hetaerina, Mnesarete, Ormenophlebia and Bryoplathanon. While several studies have focused on the intriguing behavioral and morphological modifications within Hetaerina, little of the evolutionary history of the group is well understood. Understanding the biogeographical history of Hetaerininae is further complicated by uncertainty in important geological events, such as the closure of the Central American Seaway (CAS). We generated a phylogenetic hypothesis to test the relationships and divergence times within Hetaerininae using IQtree and BEAST2 and found that Mnesarete and Ormenophlebia render Hetaerina paraphyletic. Reclassification of the genera within Hetaerininae is necessary based on our results. We also tested the fit to our dataset of two different hypotheses for the closure of CAS. Our results supported a gradual closure, starting in the Oligocene and ending in the Pliocene. Using Ancestral Character State Reconstruction, we found that the rubyspot, which is associated with higher fecundity in several species, was ancestral for Hetaerininae and subsequently lost four times. Estimates of diversification in association with the rubyspot are needed to understand the plasticity of this important character. Forest habitat was the ancestral state for Hetaerininae, with transitions to generalist species of Hetaerina found primarily in the Mesoamerican region. These results add to our understanding of the relationship between morphology, biogeography and habitat in a charismatic group of damselflies.

Incomplete premating barriers in closely related species may result in reproductive interference. This process has different fitness consequences and can lead to three scenarios: niche segregation, sexual exclusion, or reproductive character displacement. In morphologically cryptic species, isolation barriers can be difficult to recognize. Here, we analyzed the morphological, behavioral, and genetic differences between two sympatric cryptic species of the genus Hetaerina to determine the characters that contribute the most to reproductive isolation and the effect of the high rates of behavior interference between the species. We found complete genetic isolation and significant differences in the morphometry of caudal appendages and wing shape, as well as body size variation between species. In contrast, we did not find clear differences in the coloration of the wing spot and observed high rates of interspecific aggression. Our results suggest that divergence in the shape of the caudal appendages is the principal pre-mating barrier that prevents interspecific mating. Moreover, a scenario of character displacement on body size was found. Nevertheless, size could play an important role in both inter- and intrasexual interactions and, therefore, we cannot differentiate if it has resulted from reproductive or aggressive interference.

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